Nickel-base alloy



Patented Apr. 6, 1943 2,315,491 NICKEL-BASE ALLOY Joseph H. Brennan, Niagara Falls, N. Y., assignmto Haynes Stellite Company, a corporation of Indiana No Drawing. Application September 24, 1940, Serial No. 350,103

2 Claims. (01. 75-470) The invention relates to nickel-base alloys and refers more particularly to nickel-molybdenumiron alloys having improved hot working properties.

Nickel-molybdenum-iron alloys are widely used for resistance to corrosion. These alloys may, and frequently do, contain other elements such as tungsten, chromium, vanadium, manganese, and silicon, in addition to copper which is a usual impurity in alloys of this type and which is sometimes added intentionally. In some uses, articles composed of nickel-molybdenum-iron alloys are employed in the form of castings, but in other uses it is desirable that they be wrought.

Difficulty is encountered. in hot working alloys of the kind described because certain of the alloys may be hot worked readily and economically, while others of very similar composition crack or check on hot working. There is therefore a demend for'improvement in the hot working characteristics oi! nickel-molybdenum-iron alloys, and it is an important object of this invention to satisfy this demand.

In accordance with the invention, this object is achieved by maintaining the copper content of nickeLmoIybdenum-iron alloys at a proportion below a critical maximum of 0.15% and preferably below about 0.1%. The invention includes a nickel-base alloy containing to 40% molybdenum, 4% to 25% iron, copper in a proportion not exceeding 0.15%, the remainder substantially all nickel and incidental impurities. With a molybdenum content of about 10% to 25%, the iron content may be between and 25%. If the molybdenum ccntentis between 25% and 40%, the iron content should not substantially exceed 7% or 8%.

Up to 10% of tungsten may be included in the alloy of the invention and minor but effective proportions of other materials such as manganese up to about 3%. silicon up to about 1%, chromium up to about 1%, about 0.3% of vanadium, and carbon in a proportion not exceeding 1% may also be present in the alloy. A portion of the nickel may be replaced by cobalt. Traces of lead may be present as an unavoidable impurity, but the proportion of lead should in all cases be below 0.003%.

The improved hot workability of nickel-molybdenum-iron alloys in which the copper content is less than 0.15% has been demonstrated by comparlson oi the yield of /4 inch rods obtained by hot working ingots of alloys containing molybdenum, 20% iron, between 0.5% and 2.5%

manganese, 0.3% silicon, 0.3% vanadium, 0.1%

carbon. remainder nickel with varying proportions of copper. In a comparative test with a copper content oi. about 0.07%, 63.18% of the metal in the ingot was obtained in the form of /4 inch rods. .{When the copper content was increased to about 0.11%, the yield of rods "from theingot averaged about 51.6%, and with a copper proportion of 0.15% the rod yield was about 47.2%.

In similar tests ingots of alloys containing 29% molbdenum, 4.5% iron, between 0.5% and 1.5% manganese, 0.3% silicon, 0.3% vanadium, 0.1% carbon, remainder nickel and varying proportions of copper were hot worked to /i inch rods- When the copper content averaged about 0.07% the yield of rods was 51.7% of the weight of the ingot. When the copper proportion was 0.26% the yield was 40.4%. Of six heats each containing about 0.36% copper, four heats were scrapped and the maximum rod yield was 30%.

In all of the tests just mentioned the percentage yield was calculated by dividing the weight of rods produced from an ingot by the total weight of the ingot. The total weight of the ingot included the weight of a hot top from which no rods were produced, and the percentage yield of rods from usable metal of the ingot was accord ingly considerably higher than the percentage reported.

The above tests clearly'demonstrate the im proved hot working characteristics of nickel-base alloys containing molybdenum and iron obtained by limiting the copper content to a definite maximum. The alloys of the invention containing less than 0.15% (preferably less than 0.1%) copper may be used to advantage in fabricating articles required to withstand corrosion, the corrosion resistance of the alloys being unaffected by keeping the copper content at a minimum. The

use of the alloy of the invention is economical,

eliminating many failures in hot working operations and, increasing the yield of hot worked articles obtained from an ingot.

vVifhile certain specific examples of the invention have been given herein, these examples are merely illustrative of the principles of the invention, and the invention is not limited to or by such examples.

I claim:

1. In the art of manufacturing nickel-molybdenum-iron alloys containing copper as a usual impurity, the improvement which comprises maintaining the copper content of such alloys at a proportion below 0.15%, whereby to impart to said alloys hot working properties superior to' the hot working properties of substantially identical alloys containing more than 0.15% copper.

2. In the art of manufacturing nickel-base alloys containing about 10% to 40% molybdenum, 4% to 25% iron, and copper as a usual impurity, the improvement which comprises maintaining the copper content of such alloys at a proportion below 0.15%, whereby to impart to the alloys hot working properties superior to the hot working properties of substantially identical alloys containing more than 0.15% copper.

JOSEPH H. BRENNAN. 

